Installation Guide
14
Figure 18
Figure 19
SQUARE PORTION 
OF SUPPORT BOX 
NEEDS A MIN OF 2 
INCHES CLEARANCE TO 
FINISHED CEILING
18 INCH MIN CLEARANCE 
FOR SINGLE-WALL 
STOVEPIPE
CAP ADJUSTABLE 
FLASHING
CHIMNEY 
SECTION
STORM 
COLLAR
CHIMNEY 
SECTION
FRAMED 
OPENING
SQUARE 
CEILING 
SUPPORT BOX
OR REDUCED 
CLEARANCE 
SUPPORT BOX
CHIMNEY 
SECTION
CHIMNEY 
SECTION
CAP
ADJUSTABLE 
FLASHING
CHIMNEY 
SECTION
STORM 
COLLAR
SQUARE 
CEILING 
SUPPORT BOX
OR REDUCED 
CLEARANCE 
SUPPORT BOX
CHIMNEY 
SECTION
Installation Instructions for directions on how 
to install the remainder of the Combustible Air 
System. The Support Box must remain level, 
and the top edge of the box must cover the 
edge of the roof’s decking material. Square 
Ceiling Support Boxes are available in 11-inch, 
24-inch, and 36-inch heights. The Reduced 
Clearance Support Box is available in 24” 
length for 6” diameter chimney only. Mobile 
home chimney installations are roof supported.  
Do not seal openings in ashing. 
1. Place Appliance: Place the appliance in its 
proper location, referring to the manufacturer’s 
instructions as to allowable distances from 
combustibles, etc. 
2. Cut Openings: Cut a roof opening in your 
desired location, just as in a Ceiling-Supported 
Installation (Steps 1 through 5). If a separate 










